Every animal or plant species has a double-barreled or ‘binomial’ scientific name, translated into Latin by the first person to classify it. Choosing to write scientific names in Latin was first proposed by the 18th century Swedish naturalist, Carl Linnaeus.

Carl Linnaeus

Everyone can use the same name no matter what their native language. In the UK there is a plant that is known by over 90 different names:

It’s know as Lords and Ladies, Cuckoo Pint, Jack in the Pulpit, Starchwort, Sucky Calves,  and many other names related to it’s appearance. It is widespread and in each country it has a range of names. Thanks to Linnaeus, there is only one scientific name for every plant and it is the same name whichever country you are in or whatever language you speak – this particular plant is universally known by it’s Latin name Arum maculatum. 

Latin names are usually italicised or underlined.

The tree above is called Pinus sylvestris which means ‘pine of the woods’ in Latin.

The first part of the ‘binomial’ is the ‘generic’ name and begins with a capital letter. Pinus in our exampleIt is shared by all of the species belonging to the same genus (closely related group). The ‘generic’ first name is often descriptive, giving a clue to some general feature of that type of tree. Pinus is the genus and sylvestris is the species

sylvestris (always italicised and in lower case) is the specific name and was decided upon based on one of these things:

  • a unique characteristic of that one particular species (such as colour or size)
  • where it comes from (habitat, country) – sylvestris means ‘the woods’
  • who discovered it.

Within the members of any one species there are often small natural local variations in shape, size or colour which are inherited genetic features and not just caused by the place or the conditions it grows under.

Where these clear and genetically inherited differences occur in the wild, the trees are called ‘varieties‘ and a third Latin or scientific name is added on the end. For example, the Highland variety of Scots pine with its distinctive short, blue-green needles becomes Pinus sylvestris var. Scotica.

When species of trees from the same genus but native to different parts of the world are brought together by human actions a hybrid may result which shows characters of both parents. One example occurred at Dunkeld in Scotland, where European and Japanese larches, normally found continents apart, were planted near each other and cross-fertilised producing the hybrid or Dunkeld larch. Its scientific name is written Larix x eurolepis. The x between the names indicates that both parents of this hybrid originate from the same genus.

More rarely, a hybrid arises between species coming from different genera. The Leyland cypress (commonly planted for hedges and screens in this country), is a sterile cross between two American species; the Monterey cypress (Cupressus macrocarpa) and the Nootka cypress (Chamaecyparis nootkatensis). An x symbol is placed before the scientific names of such hybrids; so the Leyland cypress becomes x Cupressocyparis leylandii.
The Nootka cypress has been transferred recently to a new genus; its new name is Xanthocyparis nootkatensis so Leyland cypress should figure as x Cuprocyparis leylandii from now on.

The same information is stated differently on websites like rfs.org.uk with a little more detail  – worth visiting in case it is easier to understand – they put it like this:

genus is “a group of closely related species possessing certain morphological characters in common, by which they are classified and distinguished from all others.”

The genus Quercus includes every oak on the planet. The genus Acer includes many species of ‘maple’, the Norway maple, Acer platanoides etc, and also Sycamore. ‘Generic’ names like Acer are always spelt using an upper case initial letter when using a combination of upper and lower case letters.

species (abbreviated to SP.) is ‘‘a sub-division of a genus consisting of plants which have the same constant and distinctive characters and which have the capacity to interbreed amongst themselves.’’ – in other words, the basic unit of classification and nomenclature.

For instance the scientific name of the Sessile Oak tree is Quercus petraea. This means that is a species within the genus Quercus and has a specific name of petraea. All oaks worldwide are members of the Quercus genus but they are not all the same species. Quercus robur, for instance, is another species of oak, commonly called the Pendunculate Oak or the English Oak (but only in the U.K!), Then there is Quercus cerris (the Turkey Oak), Quercus ilex (the Evergreen) or Holm Oak, Quercus rubra, the Red Oak and so on. All of these species are sufficiently similar to be identified as oaks and therefore within the genus Quercus, but sufficiently different to be separate species.

The ‘specific’ name may refer to a characteristic feature of the plant. Quercus rubra is the Red Oak (rubra, obviously, is the latin for red). Populus alba is the White Poplar.

Specific names are always spelt using lower case letters when using a combination of upper and lower case letters e.g. Quercus rubra

Sub-species (SUBSP), varieties (VAR) and forma (F) are ‘‘sub-divisions of a species, consisting of plants which differ in some heritable characters such as form, colour or season, from what is regarded as typical of the species.’’

Botanists identify sub-species, varietas (or more commonly ‘‘variety’’) or forma within species. The tree Sorbus domestica can take many subtly-different shapes – one variant has apple-shaped fruits and so has ‘maliformis‘ added to it’s name: Sorbus domestica maliformis
The addition of the third word identifies the plant by describing a particular characteristic of this variety. Botanists identify subspecies, varieties or forma, but for most of us there is usually no need. In pet terms, all dogs are sub-species of canis familiaris and are capable of breeding with each other but need an extra word at least to identify them.

Cultivars (CVS.) are ‘‘an internationally agreed term for a cultivated variety’’

clone as ‘‘genetically uniform group of plants originating from a single plant by vegetative propagation.’’

A variety within a species is usually a departure from the ‘typical’ botanical characteristics. Cultivars are selected by the grower for their advantages – they can be created by vegetative propagation or in the case of ‘true’ breeding cultivars, by seed.

Acer platanoides (Norway Maple) trees have green leaves. By chance, a cultivar was created that has deep purple leaves, so it was name Acer platanoides ‘Crimson King’. We can tell simply from the name that it must be a cultivar of Acer platanoides ) selected. It is easier to maintain in cultivation by vegetative means than relying on seed. Clones are the vegetatively produced offspring from a single parent and are, therefore identical to the parent in all respects. To reproduce clones that we like, we clones them vegetatively so they remain identical to their parents – Acer platanoides ‘Crimson King’ is exactly like the green leafed Acer platanoides except for its leaf colour.

It is not, therefore, difficult to identify a variation of a particular species and the cultivar name qualifies the species name. However, through selection, hybridisation and mutation, it is not always easy to link a cultivar name to a species or hybrid. An example is Prunus ‘Snow Goose’. Its exact botanical origins are in doubt but it is a cultivar within the genus Prunus which has been selected and continues to be propagated. In these instances the species name is left out.

Genusspecies and variety are written in italics with a combination of upper and lower case letters, cultivar names are in Roman letters, with an upper case initial and within single inverted commas e.g. Fraxinus excelsior ‘‘Westhof’s Glorie’ or Sorbus ‘Sheerwater Seedling’

hybrid is ‘‘a plant raised by the crossing of two genetically distinct plants’’.

The characteristics that go to make up a species are normally a result of ‘natural’ breeding. However hybridisation (which is not normal because it is performed on the plant by people) is uncommon in nature. Hybrids may result from the crossing of species (bi/specific) or even more rarely, the crossing of genera (bi-generic).

For example, the result of crossing the species, Aesculus hippocastanum

with Aesculus pavia

is Aesculus x carnea

The resultant plants exhibit characteristics of both parents but differ between themselves and so have been given a range of cultivar names, e.g. Aesculus x carnea ‘Briotii’. The well known Leyland Cypress, x Cupressocyparis leylandii is an example of a bi-generic hybrid. In this instance the cross was between two species in different genera, Chamaecyparis nootkatensis and Cupressus macrocarpa.

Hybrids are identified by the symbol ‘x’ , which for a bi-specific hybrid occurs before the specific name,

e.g. Sorbus x thuringiaca

and for a bi-generic hybrid to occurs before the generic name – x Crataemespilus
Wikipedia define three types of hybrids:

  1. Offspring resulting from the interbreeding between two animal species or plant species.
  2. Hybrids between different subspecies within a species (such as between the Bengal tiger and Siberian tiger) are known as intra-specific hybrids. Hybrids between different species within the same genus (such as between lions and tigers) are sometimes known as interspecific hybrids or crosses. Hybrids between different genera (such as between sheep and goats) are known as intergeneric hybrids. Extremely rare interfamilial hybrids have been known to occur (such as the guineafowl hybrids). No interordinal (between different orders) animal hybrids are known.
  3. Cosses between populations, breeds or cultivars within a single species. This meaning is often used in plant and animal breeding, where hybrids are commonly produced and selected because they have desirable characteristics not found or inconsistently present in the parent individuals or populations. This flow of genetic material between populations is often called hybridisation.

More technical information: International Commission on Zoological Nomenclature.